Tar composition



Patented Feb. 26 I935 TAR COMPOSITION William H; :Kershaw, :Forest- Hills, N. Y., assignor to The ,Texas- -Gompany, New York, N. Y., a corporation of Delaware 1 No Drawing. Application July 31, '1931, Serial No. 554,372. In Canada July 22, 19 30 The invention contemplates an improved tar composition comprising a'mi'xture ,of a tar derived from coaland a petroleum tar which is miscible therewith in all proportions. More specifically the. invention contemplates the prep,- aration of mixtures of tars derived from coal or water gas ,tar, gas works tar and the like, with a petroleum tar obtained by the ,thermal rconversion of mineral oils for the production of 20 motor fuel.

The petroleum tar, or pitch, to which the invention ,has reference is obtained by cracking mineral oils-for the production of gasoline as practiced,,for example, in the coil type,-the shell still type, the coiland still type,.or the tubeland tank type, of cracking process and wherein the oil is subjected to heat treatment in either the vapor or liquid phase under superatmospheric pressures, or atleast at pressures substantially cabove atmospheric. Such operations produce only a relatively small percentage of gas, a large percentage of gasoline or motor fuel, andacom siderable amountof heavy oil which is either cyclicallydistilled in this processor distilled in a 5 separate operation to form a distillate charging stockand a tarry residue.

The heavy tar orpitch product resulting from this type of cracking operation, while sometimes referred to as cycle fuel tar, is quitefgenerally 40 known .in the'industry as pressure tar, and it will be hereinafter referred to as petroleumpressure tar. 3

petroleum pressure ter is to be distinguished fromfthe so-called-petroleum residues re- ,sultingfrom the ordinary distillation of'petroleum for the production of distillates. of

thekerosne ;or gas oil type and where only incipient or very slight cracking takes place,

and the resulting residual. material is practically :likeordinarycrude ,oil residue. It isalso to-be differentiated, on the other hand, from the-tars produced by the ,very drastic crackingof gas oil-for the manutacturenof oil gas, which :tars really ;fall:almost directly into the coal :tar {classy 5.5 being .devoid;of-the many-desirable; characteristics coal products, such as. coal tar, ,coke oven tar,

I tars derivedfrom coal products, areyerysuScepis of value.

ofpressure tar and, therefore, incapable of 7 carrying into, ,or imparting to, a ztar composition the advantages anddesirablecharacteristics of the composition-of myinvention.v

Heretofore, tar compositions for use in road construction, or as waterproofing, or surfacing materials, have been prepared which comprised mixtures; ofcoal tar withsmallamountsof petroleum residuelobtained from the ordinary-distillation=of crude petroleumiand which residues havebeensubjected to relatively veryslight'cracking only, as already mentioned. These mixtures have been unsatisfactory since such petroleum residuesarelnotatrulymiscible with coal tars. On account of their ,wide divergence in character, it hasbeen impossible. to produce stable homogeneous compositions. ,At.most, it is impossible to mix more than 20% or 25% of such petroleum residue with coal tars, and mixtures in which the petroleum content exceeded this amount haveibeen entirely unsatisfactory.

Coal tars are useful in the trade on account of theirquick-setting properties and'rapid bondingqualities. On the other hand, coal:tars, or

tible to changes in atmospheric temperature;

They become quite soft "at summer temperatures and quite 'brittle atwinter temperatures: as a result of which 'paving'and surfacing material's composed substantially-entirely of coal tars or tars derived from coal :are subject to rapid deterioration;andcfailure in service. 1'

In using tars of thecoalltar type 'innthe-zcon struction and maintenance of bituminous :roadways, the-quick-setting properties of these tars,

when .ordinary petroleumv residues derivedfromthe simpledistillation ofvcrude petroleum are admixed with the tar, .the quicksettingproperties of the tarmaybeimpairedto Y a greater or lesser extent. Ihave discovered, however, that petroleum pressure tars donotact like the ordinary petroleum residues and that such petroleumpressuretars may be, admixed with coal tarto yield a product possessing .the' quick-setting and rapid bonding qualities of a straight coal tar product. Furthermore, the product thus obtained possesses" a high degree -01: ductility and adhesiveness; i

This petroleumpressure tarobtained by'the cracking of mineral oils for the production of gasolineis completely miscible with coal tars or tars deriveditherefrom in all proportionstand at moderate temperatures Also, contrastedwithcoal tarsypetroleum :pressure star issmuch I less Pressure Coal tar Melting point F 122 Ducility at 77 F 75 Above approximately 140 F. melting point, the ductility of the petroleum pressure tar may drop off rapidly and it is, therefore, advantageous to employ a petroleum pressure tar having a melting point not in excess of about 140 F. where a tar composition of very high ductility is desired.

Since petroleum pressure tar is miscible with coal tars in all proportions, it may,v therefore, comprise from 75% to 85% of the composition and result in a product which retains not only the quick-setting and rapid bonding advantages of the coal tar but also has the greater stability and wearing qualities of the petroleum pressure tar, making the composition a better product than either of its ingredients and yet a product/which will meet all the specifications and uses to which coal tars have heretofore been put.

My improved composition is particularly well adapted for use as a road tar and, when properly prepared, is in'all respects equal to and superior to the road tars usually made in coal tar residuals and conforms to the specification requirements commonly in use. Its use, however, is not limited and it can be employed successfully as a pipe coating, for waterproofing as a binder, in coal briquetting, in the manufacture of prepared roofing and roofing composed of alternate layers of saturated felt and bituminous material, and for other purposes where coal tars have been considered particularly desirable, and the following description, which refers particularly to road tars, is 'only by way of illustrating one manner in which my invention may be employed and not as alimitation of my invention.

Among the general types of tars commonly used by road contractors are heavy binders, cold patches and surfacing materials; and these tars can be readily made according to my invention.

The heavy pitch or binder of my invention may also be used under certain State specifications as a base for the lighter grades of tar for cold and hot surfacing; and I have discovered that I can produce specification materials by thinning my heavy'binder to the proper consistencywith the distillate from water gas tar or-a coal tar, such as coke oven tar or gas works tar. In order to meet the distillation test of certain specifications, such as, for instance, the cut back product used for cold patch, it is necessary to redistil the water gas tar distillate and to use-a blend of the original distillate with a predetermined fraction. The redistillation can, however, be avoided by utilizing a fractionating column in connection with the tar distilling apparatus and taking off sufficient distillate to form a residual product of the desired consistency.

In making the road tars of my invention, I first take a petroleum pressure tar and reduce it by distillation to a pitch of the proper consistency, unless it is already sufficiently reduced in the cracking process. I then mix with the pitch a tar such aswater gas tar or coke oven tar, or the oils or pitches produced therefrom which are miscible with. the pressure tar and the pitches produced therefrom, at moderate temperatures and in all proportions, forming perfectly homogeneous mixtures which possess the characteristic odor and appearance of tar and the high ductility and extreme stickiness common to liquid and semi-liquid tar products.

The water gas tar or coke oven tar may or may not be reduced bydistillation prior to mixing with the pitch made from the pressure tar, depending upon the characteristics of the. materials themselves. The actual mixing of the pitch from pressure tar and water gas or coke oven tar can be carried out many suitable manner. In these mixtures the petroleum pressure tar is generally the major component. In some instances I have found it desirable to add to the aforesaid mixtures a relatively small percentage of a suitable distillate such as that produced during the distillation of water gas or coke oven tar. The analyses of the resulting mixtures conform fully to the road tar specifications commonly used.

I have found that the heavy binder constitutes a suitable base for the production of lighter surfacing material or cold patch material when out back with a distillate which may be obtained from the distillation of water gas or coke oven tars, the proportions of the two materials depending upon the characteristics of the materials themselves and the specifications to be met. It will be understood by those skilled in the art that, owing to the inherent variability in the characteristics ofv tarsin general, it is necessary to vary the proportions of all of the materials used and the procedure, therefore, requires continued laboratory control by analyses of the component materials and the final products.

It is obvious that pitches of various consistencies or tars of various consistencies can be used in carrying out my invention, but as illustrative of a particular method employed to meet a definite requirement, I give the following example:

I take a petroleum pressure tar and reduce it by heat and steam to form a pitch of about 154 F. melting point and having a specific gravity at 77 F. of about 1.18, removing usually about 25% of distillate. I then take a tar of relatively low viscosity of the type of water gas tar or coal tar, and reduce it by heat toa suitable consistency for fluxing the petroleum pressure tar, ordinarily taking off about 25% of distillate. The reduced water gas tar has a specific gravity at 77 F. of about 1.095. The petroleum pressure tar and the reduced tar are then mixed in' the proportion of 75% of the former and 25% of the latter, and this mixture is then cut back With a tar distillate, in the proportion of 95% of themixture and 5 of the tar distillate, which may conveniently be distillate from the water gas tar. The tar distillate has a specific gravity of about .920, an initial boiling point of 200 F. and an end point of about 450 F.

The mixture so produced constitutes a heavy binder, and its qualifications are shown in the following table in comparison with the specifica tion limits ofthe New Jersey specification for heavy binder (low carbon type), which specification is typical of those in common use:

- Product Speclficatlon limits (N. I.) g g g Specific gravity at 77 F 1.15 to 1.205. 1.161 Float test at 122 F 80 to 110 seconds. 84 Insoluble in CS2 5% maximum.

1% maximum. 3% maximum. 3% 11% maximum. 7% 0 to 572 F 22 0 maximum. 13% Melting point of residue 149 F. maximum. 128 F Product Specification limits (N. I.) g f gf Specific gravity at 77 F 1.09 to 1.165. 1.110 Viscosity engler 104 F. 50cc 407 to 51:! seconds 471 Insoluble in OS; maximum. Distillation Method D20-28T:

0 to 338 F 3 to 3% 14% 19% 24. 5% 138 F.

A preferred embodiment of my invention has been illustrated and described for the purpose of showing one way in which the invention may be practiced, but the inventive idea upon which this application is based is broader than this illustrative embodiment thereof. For example, I have referred to certain tars such as water gas tar, coke oven tar and gas works tar, but my invention is not to be construed as being limited to the use of these tars only, and the tars mentioned specifically are merely illustrative of the class or type of materials contemplated by my invention. My invention is not, therefore, to be limited by this disclosure, reference being had to the appended claims for that purpose.

I claim:

1. An adhesive asphaltic tar composition having a high degree of ductility combined with quick-setting properties, comprising a mixture of a tar derived from a coal product and a petroleum pressure tar which is miscible therewith in all proportions to form mixtures which are stable in the absence of a stabilizing agent.

2. An adhesive tar composition forming a heavy road binder and having a high degree of ductility combinedwith quick-setting properties, comprising a mixture of a gas works tar and a petroleum pressure tar which is miscible therewith in all proportions to form mixtures which are stable in the absence of a stabilizing agent.

3. An adhesive tar composition forming a heavy road binder and having a high degree of ductility combined with quick-setting properties, comprising a mixture of a gas works tar and a petroleum pressure tar having a melting point not in excess of 140 F. and miscible therewith in all proportions to form mixtures which are stable in the absence of a stabilizing agent.

4. An adhesive tar composition forming a heavy road binder and having a high degree of ductility combined with quick-setting properties, comprising a mixture of a coal tar and a petroleum pressure tar which is miscible therewith in all proportions, said mixture comprising a larger proportion of petroleum pressure tar than of said coal tar and forming a mixture which is stable in the absence of a stabilizingagent.

5. An adhesive tar composition forming a heavy road binder and having a high degree of ductility combined with quick-setting properties, comprising a mixture of a tar derived from a coal product and a petroleum pressure tar which has been reduced by distillation and which is miscible therewith in all proportions to form mixtures which are stable in the absence of a stabilizing agent.

6. An adhesive tar composition forming a heavy road binder and having a high degree of ductility combined with quick-setting properties, comprising a mixture of a residual tar formed by distilling tar derived from a coal product and a petroleum pressure tar which has been reduced by distillation, and which is miscible therewith in all proportions to form mixtures which are stable in the absence of a stabilizing agent.

7. A composition adapted for use in the construction and maintenance of bituminous roadways, comprising a heavy road binder formed as a mixture of a tar derived from a coal product and petroleum pressure tar which is miscible therewith in all proportions forming mixtures which are stable in the absence of a. stabilizing agent, and softened or cut back with a distillate obtained in the distillation of the tar derived from coal,

8. A composition adapted for use in the construction and maintenance of bituminous roadways, comprising a heavy road binder formed as a mixture of a tar derived from a coal product and and softened or cut back with a distillate obtained in the distillation of gas works tar.

WILLIAM H. KERSHAW. 

